intel, tests: fix -Wswitch warnings
diff --git a/tests/xglrenderframework.cpp b/tests/xglrenderframework.cpp
index a037f77..f68e085 100644
--- a/tests/xglrenderframework.cpp
+++ b/tests/xglrenderframework.cpp
@@ -697,6 +697,9 @@
         m_stride = 4;
         viewFormat.channelFormat = XGL_CH_FMT_R32;
         break;
+    default:
+        assert(!"unknown index type");
+        break;
     }
 
     alloc_info.sType = XGL_STRUCTURE_TYPE_MEMORY_ALLOC_INFO;